Prior to the present invention, various epoxy resins and vinyl organic compounds were readily photopolymerized to different cured decorative or protective coatings, as shown by Noguchi et al, U.S. Pat. No. 3,933,509 and my U.S. Pat. Nos. 4,058,400; 4,058,401; 4,069,055 and 4,069,056 assigned to the same assignee as the present invention.
In my U.S. Pat. No. 4,173,551, a wide variety of heat curable cationically polymerizable organic materials are shown which can be converted to the cured tack-free state in the absence of radiant energy by the use of a cationic curing catalyst in the form of a diaryliodonium salt and a copper salt. Other heat curable compositions also are shown in U.S. Pat. No. 4,230,814 assigned to the same assignee as the present invention, wherein there is described the use of a certain hydroxyaryldialkylsulfonium salts and organic peroxide to effect the cure of various cationically polymerizable organic materials.
Although valuable cured coatings and a wide variety of shaped high performance reinforced structures can be made by the above-mentioned procedures utilizing different forms of energy with diverse cationically polymerizable organic materials and an appropriate cationic curing catalyst, those skilled in the art know that in many instances, optimum heat curable molding compositions are often not available. An optimum heat curing molding composition, for example, would cure to a product at a temperature in the range of 100.degree. C. to 180.degree. C. exhibiting a heat distortion temperature of about 90.degree. C. in about 60 to 180 seconds.
It has been found that alkyl vinyl mono ethers do not provide optimum heat curable molding compositions because such materials often cure to tacky materials. In addition, polyalkylvinylethers, for example diethylene glycol divinylether, are often so reactive, when heated in the presence of a heat activated cationic curing catalyst that the resulting cured material is often charred. Improved results have been achieved with epoxy resins, but in many instances these materials often require a cure of several minutes, particularly in instances where aryl-substitution is utilized, such as the diglycidyl ether of bisphenol-A to improve the heat distortion of the resulting cured product. Efforts to reduce the molecular weight of such materials to improve the cure speed often increase the risk of toxicity of the resulting epoxy resin due to its greater volatility.
The present invention is based on the discovery that certain aromatic polyvinylethers, for example, 2,2-bis(p-vinyloxyethoxyphenyl)propane, and reaction products of such materials with various active hydrogen compounds, for example, polycarboxylic acids, phenols, silanes, thiols, etc., can be utilized with a variety of heat activated cationic curing catalysts, to produce optimum molding compositions. Depending upon the nature of the aromatic polyvinylether, or reaction product thereof, a wide variety of heat curable compositions are provided which can be used for various molding applications.